Markers and buttons for Storyline 360

I have a slide with 10 pictures and each has a marker with text that appears when the marker is clicked.

#1 I have the 10, individual pictures on the base layer.   I created a new layer for each of the 10 markers.    I then added a trigger on the base layer to show the layer when the audio media ends.  However, when I preview, the only marker that appears is the last one.

How do I get each marker to appear at the same time when the media ends?

 

#2  I have a current trigger for each individual marker to change the state of picture 1 to hidden when the content closes .  The object for that trigger is 'picture 1'.

The content automatically closes when the user clicks the next marker.  I'm not sure if that is the best trigger to use to make that picture/marker unavailable.   What are your suggestions?

 

#3  Users can click those 10 pictures in any order they chose.  I would like to have a 'next' button appear when the last marker is selected.   I can add a trigger to have the button appear when a certain marker is clicked but I am not discovering a way to have it appear only when the last marker is clicked.

I tried adding a layer to appear when the timeline reaches a certain point, and the same with the button but it's not working for me.